The present invention relates to blades for termination tools which connect wires to an array of insulation displacement terminal clips, such as those used on a patch panel or the like. Such tools are commonly referred to as punch down tools because they assist in pushing the wires down between the prongs of the termination clips. Typically, the blades are reversible and have two opposite ends. One of the ends may have a cutting edge which trims a wire just beyond the terminal clip while the other end may have a non-cutting, seating only, edge which seats the wire in the clip without cutting the wire. Common blade types are the 66-type, which is generally used in the telephone industry to connect to a 66 terminal, and the 110-type, which is used for 110 data and computer terminals. A punch down tool of this general character is shown in U.S. Pat. No. 4,241,496, the disclosure of which is incorporated herein by reference.
During insertion of a wire into a terminal clip, the seating edge of the blade end spreads the terminal prongs to allow insertion of the wire into the terminal. As the wire is pressed into the terminal clip, the clip itself will split, pierce or otherwise displace the insulation to allow the terminal to make electrical contact with the wire""s underlying conductor. If the blade end is a non-cutting or seating only edge, then the wire will be pushed into the terminal clip without any trimming occurring. If the blade end has both a seating and cutting edge, then the wire is pushed into the terminal clip and the blade simultaneously trims a portion of wire which protrudes from the clip.
In order to push the wire into the terminal clip and displace the insulation, a large force must be applied to the tool. Over time punch down tools and blades undergo a high number of wire installations and must withstand the force from numerous impacts in every blade and terminal setting. Thus, they must be highly durable and strong. The difficulty in forming the blade is compounded where a seating edge and a cutting edge are combined on one end of the blade. The material comprising the blade not only has to have characteristics of strength and durability, but the properties of the material have to provide both cutting and seating edges.
Traditionally blades have been made of only one piece of material because the formation and material of the blades are driven by the required performance characteristics. Prior punch down blades are made of cast steel which provided the required strength and durability needed by the blade. Steel also satisfies the combined characteristics of strength of the seating edge for pushing the wire into the termination clip and sharpness of the cutting edge for termination of the wire at the clip.
Steel further can withstand the force which occurs when an internal spring-loaded, impact mechanism is used. The impact mechanism applies consistent impact during the punch down operation and reduces the effort required by the operator to terminate and cut wiring for a proper connection. When the operator pushes down on the tool, the spring is compressed and causes corresponding compression in the tool head which holds the blade. After a predetermined force has been applied to the spring, it is unseated and returns the tool head and blade to the uncompressed length thus causing an immediate push down force to be applied to the wire and terminal connection. While the impact mechanism is intended to reduce operator fatigue, it does not reduce the amount of force which is being applied to the blade. As a result, the impact mechanism has reinforced the traditional belief that the blade construction be a one-piece construction of steel.
However, using all steel to make the blade can be relatively costly and the finishing steps to provide a dual cutting and seating edge made of steel can be time consuming. There is a need to provide a blade which is less costly to make while also providing a blade which meets the same durability, strength and cutting requirements. It is also advantageous to provide a blade which is made of several pieces of material instead of one cast piece.
The present invention provides a multi-piece punch down blade assembly where two or more pieces are combined to form a blade assembly with a minimum of attachment points. Particularly, a cutting edge of the blade assembly is separately attached to the blade assembly by one or more attachment points. The pieces of the blade assembly can be made of different materials.
The punch down blade assembly of the present invention has a base member which includes a mounting block and at least one extension connected at one end to the mounting block. The other, free end of the extension terminates at a wire-engaging head. A blade-receiving shoe is formed in or on the extension. The extension also has an abutment adjacent the shoe and overlying it slightly to form a notch. An attachment element extends from the shoe. The notch and attachment element retain a cutting blade on the shoe. The cutting blade has a front or cutting edge that extends beyond the end of the wire-engaging head. The cutting blade has a rear edge that fits into the notch to engage the abutment. The base member is preferably made of glass filled plastic, such as nylon. The cutting blade is preferably made of steel.
The present invention provides a blade assembly which can be made at a lower cost than current blades while still providing a strong, durable blade and sharp cutting edge that can withstand repeated terminations.